Coriander can be used in both sweet and savory applications. Whole seeds are typically lightly toasted before use in savory dishes, but used raw in sweet ones. Coriander seeds can be used whole, crushed, (they have thin walls, making this easy) or ground.
In addition to being used crushed or ground in a huge variety of recipes, coriander can also be used whole in pickling solutions, marinades (traditionally for pork & game meats), mulled wine, and infused alcohols (gin is the most common).
Ground coriander not only imparts flavor, but can also be used as a thickener in sauces.
For savory use, pair coriander with ingredients like seafood, poultry, game meats, pork, ginger, carrots, vinegar, cabbage, chilies, crab, citrus fruit, lentils, and a wide variety of spices (especially cumin).
In sweet dishes (often Scandinavian in origin) pair coriander with ingredients like apples, cardamom, dried fruit, saffron, plums, quince, and traditional autumn spices (cloves, nutmeg, anise, mace, etc).